Image sensors including phase detection pixel

ABSTRACT

An image sensor is presented which includes a pixel array including a plurality of image sensing pixels in a substrate, a phase detection shared pixel in the substrate, the phase detection shared pixel including two phase detection subpixels arranged next to each other, a color filter fence disposed on the plurality of image sensing pixels, and the phase detection shared pixel, the color filter fence defining a plurality of color filter spaces, a plurality of color filter layers respectively disposed in the plurality of color filter spaces on the plurality of image sensing pixels, and the phase detection shared pixel, a first micro-lens disposed on each of the plurality of image sensing pixels to have a first height, and a second micro-lens disposed to vertically overlap the two phase detection subpixels of the phase detection shared pixel and to have a second height greater than the first height.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2019-0131579, filed on Oct. 22, 2019, in the Korean IntellectualProperty Office, and U.S. patent application Ser. No. 16/986,759, filedon Aug. 6, 2020, the disclosures of which are incorporated by referenceherein in their entirety.

BACKGROUND

The inventive concept relates to an image sensor, and more particularly,to an image sensor including phase detection pixels.

Image sensors are devices used to capture light information and convertthe captured light information into an electrical signal to create animage. Image sensors are present in numerous devices. For example, theyare used in cameras, phones, medical imaging devices, thermal imagingdevices, and night imaging devices.

In some cases, image sensors include image sensing pixels which receivelight and convert the received light into an electrical signal. Imagesensors may also include numerous photodiode regions, where an autofocusing function may be performed by an image sensor to accuratelycapture an image for a short time.

A micro-lens is a small lens located on an image sensing pixel. Amicro-lens may be used to provide quality optics to the image sensor.Micro-lenses on image sensing pixels may be produced at the same time,e.g., during the same manufacturing process. However, simultaneousproduction of micro-lenses may result in non-optimized lenses. Forexample, all lenses that are produced might be uniform. Butcustomization of micro-lenses for different image sensing pixels canprovide improved optics for an image sensor. Therefore, there is a needin the art for manufacturing processes capable of producing differentmicro-lenses for different image sensing pixels of an image sensor.

SUMMARY

The inventive concept provides an image sensor which quickly andaccurately performs an auto focusing function and enhances a sensitivityof an image sensing pixel.

According to an aspect of the inventive concept, there is provided animage sensor including a pixel array, wherein the pixel array includes aplurality of image sensing pixels provided in a substrate, a phasedetection shared pixel provided in the substrate, the phase detectionshared pixel including two phase detection subpixels arranged next toeach other, a color filter fence disposed on the plurality of imagesensing pixels and the phase detection shared pixel, the color filterfence defining a plurality of color filter spaces, a plurality of colorfilter layers respectively disposed in the plurality of color filterspaces on the plurality of image sensing pixels and the phase detectionshared pixel, a first micro-lens disposed on each of the plurality ofimage sensing pixels to have a first height, and a second micro-lensdisposed to vertically overlap the two phase detection subpixels of thephase detection shared pixel and to have a second height which isgreater than the first height.

According to another aspect of the inventive concept, there is providedan image sensor including a pixel array, wherein the pixel arrayincludes a plurality of image sensing shared pixels each including aplurality of image sensing subpixels corresponding to a color filterlayer having the same color, a plurality of phase detection sharedpixels each including two phase detection subpixels configured togenerate a phase signal for calculating a phase difference betweenimages, and a micro-lens structure disposed on the plurality of imagesensing shared pixels and the plurality of phase detection sharedpixels, and the micro-lens structure includes a first micro-lensdisposed on each of the plurality of image sensing pixels to have afirst height and a second micro-lens disposed on the two phase detectionsubpixels to have a second height which is greater than the firstheight.

According to another aspect of the inventive concept, there is providedan image sensor including a pixel array, wherein the pixel arrayincludes a plurality of image sensing pixels provided in a substrate, aphase detection shared pixel provided in the substrate, the phasedetection shared pixel configured to generate a phase signal forcalculating a phase difference between images, the phase detectionshared pixel including two phase detection subpixels arranged next toeach other in a first direction parallel to an upper surface of thesubstrate, a pixel separation structure disposed between the pluralityof image sensing pixels, between the two phase detection subpixels, andbetween the phase detection shared pixel and an image sensing pixeladjacent thereto to pass through the substrate, a color filter fencedisposed on the plurality of image sensing pixels and the phasedetection shared pixel, the color filter fence defining a plurality ofcolor filter spaces, a plurality of color filter layers respectivelydisposed in the plurality of color filter spaces on the plurality ofimage sensing pixels and the phase detection shared pixel, a firstmicro-lens disposed on each of the plurality of image sensing pixels tohave a first height, and a second micro-lens disposed on the two phasedetection subpixels to have a second height which is greater than thefirst height, and a center line of the second micro-lens in the firstdirection vertically overlaps a portion of the pixel separationstructure disposed between the two phase detection subpixels.

According to another aspect of the inventive concept, a method ofmanufacturing an image sensor is described, the method comprising:providing a plurality of pixels on a substrate, wherein the plurality ofpixels includes one or more first pixels and one or more second pixels;providing a first micro-lens on each of the one or more first pixelsusing a first process; and providing a second micro-lens on each of theone or more second pixels using a second process, wherein the firstmicro-lens comprises a different shape from the second micro-lens.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the inventive concept will be more clearly understoodfrom the following detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a block diagram illustrating an image processing deviceaccording to embodiments;

FIG. 2 is a block diagram illustrating an image sensor according toembodiments;

FIG. 3 is a layout view illustrating an image sensor according toembodiments;

FIG. 4 is a cross-sectional view taken along line A1-A1′ of FIG. 3;

FIG. 5 is a horizontal cross-sectional view of a region CX1 of FIG. 3cut at a first level LV1 of FIG. 4;

FIG. 6 is a plan view of the region CX1 of FIG. 3;

FIG. 7 is an equivalent circuit diagram of a plurality of pixels of animage sensor according to embodiments;

FIG. 8 is a cross-sectional view illustrating an image sensor accordingto embodiments;

FIG. 9 is a horizontal cross-sectional view of a region corresponding toCX1 of FIG. 3;

FIG. 10 is a cross-sectional view illustrating an image sensor accordingto embodiments;

FIG. 11 is a cross-sectional view illustrating an image sensor accordingto embodiments;

FIG. 12 is a layout view illustrating an image sensor according toembodiments;

FIG. 13 is a plan view of a region CX2 of FIG. 12;

FIG. 14 is a layout view illustrating an image sensor according toembodiments;

FIGS. 15 to 25 are cross-sectional views illustrating a method ofmanufacturing an image sensor, according to embodiments;

FIGS. 26 to 28 are cross-sectional views illustrating a method ofmanufacturing an image sensor, according to embodiments;

FIGS. 29 to 32 are cross-sectional views illustrating a method ofmanufacturing an image sensor, according to embodiments;

FIGS. 33 to 36 are cross-sectional views illustrating a method ofmanufacturing an image sensor, according to embodiments; and

FIGS. 37 to 40 are cross-sectional views illustrating a method ofmanufacturing an image sensor, according to embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure relates generally to micro-lenses of imagesensing pixels in an image sensor. Conventional methods formmicro-lenses for different pixels during the same manufacturing. Forexample, a process might produce a micro-lens of a first pixel and amicro-lens of a second pixel at the same time based on the same processconditions. Therefore, the height of the first micro-lens of the firstpixel may be the same as that of the second micro-lens of the secondpixel. However, the curvature of the first micro-lens and the curvatureof the second micro-lens may not be optimized. As a result, separationratio characteristics, sensitivity, and signal-to-noise (SNR)characteristics of the first and second pixels can be suboptimal.

Therefore, embodiments of the present disclosure describe a process forproducing different micro-lenses for different pixels in an imagesensor. For example, a first micro-lens for a first pixel and a secondmicro-lens for a second pixel can be formed through different processes.Therefore, the curvature of the first micro-lens and the curvature of asecond micro-lens can be optimized, thereby improving pixelcharacteristics. Additionally, a grid size of the first pixel and a gridsize of a micro-lens of the second pixel may be set independently.Therefore, separation ratio characteristics of the first pixel may beimproved.

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings.

FIG. 1 is a block diagram illustrating an image processing device 1000according to embodiments.

Referring to FIG. 1, the image processing device 1000 may be a digitalimaging device for performing an auto-focusing (AF) function. The imageprocessing device 1000 may include an imaging unit 1100, an image sensor100, and a processor 1200. The image processing device 1000 may includea focus detection function for an AF function.

The imaging unit 1100 may include a lens 1110, a lens driver 1120, anaperture 1130, and an aperture driver 1140.

The lens driver 1120 may transmit or receive information about focusdetection through communication with the processor 1200. The lens driver1120 may also adjust a position of the lens 1110 based on a controlsignal provided from the processor 1200. Therefore, a distance betweenthe lens 1110 and an object 2000 may be adjusted, and a focus on theobject 2000 may be matched or mismatched based on a position of the lens1110. For example, when the distance between the lens 1110 and theobject 2000 is relatively short, the lens 1110 may deviate from anin-focus position for adjusting a focus on the object 2000. A phasedifference between images formed in the image sensor 100 may then occur.In this case, the lens driver 1120 may move the lens 1110 in a directionin which a distance to the object 2000 increases, based on the controlsignal provided from the processor 1200.

The image sensor 100 may convert incident light into an image signal.The image sensor 100 may include a pixel array PXA, a controller 210,and a signal processor 220. An optical signal passing through the lens1110 and the aperture 1130 may reach a light-receiving surface of thepixel array PXA to form a phase of the object 2000. The pixel array PXA,as described below with reference to FIG. 2, may include a plurality ofpixels PX. The plurality of pixels PX may include a plurality of imagesensing pixels IPX and a plurality of phase detection pixels PPX.

The processor 1200 may receive pixel information from the signalprocessor 220 to perform a phase difference calculation. The phasedifference calculation may be performed by performing a correlationoperation on a column signal corresponding to the plurality of pixelsPX. The processor 1200 may calculate an in-focus position, a focusdirection, or a distance between the object 2000 and the image sensor100 based on a result of the phase difference calculation. The processor1200 may output the control signal to the lens driver 1120 to move aposition of the lens 1110, based on the result of the phase differencecalculation.

FIG. 2 is a block diagram illustrating an image sensor 100 according toembodiments.

Referring to FIG. 2, the image sensor 100 may include a pixel array PXA,a controller 210, a signal processor 220, a row driver 230, and a signalread unit 240.

The pixel array PXA may be provided by units of pixels and may include aplurality of pixels PX. Each of the plurality of pixels PX may include aphotoelectric conversion region (for example, a photodiode)corresponding thereto. Each of the plurality of pixels PX may absorblight to generate an electrical charge. An electrical signal, such as anoutput voltage, may be provided to the signal read unit 240, based onthe generated electrical charge.

The pixel array PXA may include a plurality of image sensing pixels IPXand a plurality of phase detection pixels PPX. The plurality of imagesensing pixels IPX may generate image signals corresponding to theobject 2000 (see FIG. 1). The plurality of phase detection pixels PPXmay generate phase signals used to calculate a phase difference betweenimages.

The plurality of phase detection pixels PPX included in the image sensor100 may be used to adjust a focus on the object 2000. The phase signalsmay include information about positions of images formed in the imagesensor 100. Therefore, the phase signals may be used to calculate phasedifferences between the images. An in-focus position of the lens 1110(see FIG. 1) may be calculated based on the calculated phasedifferences. For example, a position of the lens 1110 allowing a phasedifference to be zero may be an in-focus position.

In embodiments of the present disclosure, the plurality of phasedetection pixels PPX may be used to measure a distance between theobject 2000 and the image sensor 100. Additionally, the plurality ofphase detection pixels PPX may be used to adjust a focus on the object2000. Pieces of additional information, such as phase differencesbetween the images formed in the image sensor 100, a distance betweenthe lens 1110 and the image sensor 100, a size of the lens 1110, and anin-focus position of the lens 1110 may be used for measuring thedistance between the object 2000 and the image sensor 100.

The controller 210 may control the row driver 230 so that the pixelarray PXA absorbs light to accumulate electrical charges or totemporarily store the accumulated electrical charges and outputs anelectrical signal based on the stored electrical charges to the outsideof the pixel array PXA. Moreover, the controller 210 may control thesignal read unit 240 to measure a level of a pixel signal provided bythe pixel array PXA.

The row driver 230 may generate control signals RSs, TXs, and SELSs forcontrolling the pixel array PXA. Additionally, the row driver 230 mayprovide the control signals RSs, TXs, and SELSs to the plurality ofpixels PX included in the pixel array PXA. The row driver 230 may alsodetermine an activation timing and a deactivation timing of each ofreset control signals RSs, transmission control signals TXs, andselection signals SELSs corresponding to the plurality of phasedetection pixels PPX based on whether to perform the AF function.

The signal read unit 240 may include a correlated-double sampling (CDS)circuit 242, an analog-to-digital converter (ADC) 244, and a buffer 246.The CDS circuit 242 may sample and hold the output voltage provided fromthe pixel array PXA. The CDS circuit 242 may doubly sample a level ofcertain noise and a level based on the output voltage to output a levelcorresponding to a difference therebetween. Moreover, the CDS circuit242 may receive a ramp signal, where the ramp signal is generated by aramp signal generator 248. The CDS circuit 242 may also compare the rampsignal with the output voltage to output a comparison result. The ADC244 may convert an analog signal, corresponding to the level receivedfrom the CDS circuit 242, into a digital signal. The buffer 246 maylatch the digital signal. The latched digital signal may be sequentiallyoutput to the outside of the signal processor 220 or the image sensor100.

The signal processor 220 may perform signal processing on data of theplurality of pixels PX received thereby. The signal processor 220 mayperform noise decrease processing, gain adjustment, waveformstandardization processing, interpolation processing, white balanceprocessing, gamma processing, edge emphasis processing, etc. Moreover,the signal processor 220 may output information about the plurality ofpixels PX to the processor 1200 to allow the processor 1200 to perform aphase difference calculation. For example, the plurality of pixels PXmay be obtained in a phase difference AF operation.

FIG. 3 is a layout view illustrating an image sensor 100 according toembodiments. FIG. 4 is a cross-sectional view taken along line A1-A1′ ofFIG. 3. FIG. 5 is a horizontal cross-sectional view of a region CX1 ofFIG. 3 cut at a first level LV1 of FIG. 4, and FIG. 6 is a plan view ofthe region CX1 of FIG. 3.

Referring to FIG. 3, the image sensor 100 may include a pixel array PXA.The pixel array PXA may include a plurality of image sensing pixels IPXand a plurality of phase detection shared pixels PPX.

The plurality of image sensing pixels IPX may be arranged in a firstdirection (an X direction) and a second direction (a Y direction), wherethe first and second directions are parallel to a first surface 110F1 ofa substrate 110. The first direction may be a column direction of thepixel array PXA. The second direction may be a row direction of thepixel array PXA. The plurality of phase detection shared pixels PPX mayinclude first and second phase detection subpixels PPXa and PPXbdisposed adjacent to each other in the first direction (the Xdirection). The plurality of phase detection shared pixels PPX may bedisposed apart from one another by a certain interval between theplurality of image sensing pixels IPX, and for example, may be disposedat a density of 1/16, 1/32, or 1/64 of the total number of pixels PX.For example, in a case where the pixel array PXA is configured toinclude sixteen pixels PX in the first direction (the X direction) andsixteen pixels PX in the second direction (the Y direction) asillustrated in FIG. 3, the plurality of phase detection shared pixelsPPX may include eight pixels PX and may be disposed at a density of1/32.

As illustrated in FIG. 4, the plurality of image sensing pixels IPX andthe plurality of phase detection shared pixels PPX may be disposed apartfrom one another by a pixel separation structure 150 in the substrate110. A photoelectric conversion region 120 may be disposed in each ofthe plurality of image sensing pixels IPX and the plurality of phasedetection shared pixels PPX.

The substrate 110 may include the first surface 110F1 and a secondsurface 110F2. Here, a surface of the substrate 110 on which amicro-lens structure 180 is disposed may be referred to as the secondsurface 110F2. A surface opposite to the second surface 110F2 may bereferred to as the first surface 110F1. In embodiments of the presentdisclosure, the substrate 110 may include a P-type semiconductorsubstrate. For example, the substrate 110 may be a P-type siliconsubstrate. In additional embodiments of the present disclosure, thesubstrate 110 may include a P-type bulk substrate and a P-type or N-typeepi layer grown thereon. In other embodiments, the substrate 110 mayinclude an N-type bulk substrate and a P-type or N-type epitaxy layergrown thereon. Alternatively, the substrate 110 may be an organicplastic substrate. The photoelectric conversion region 120 may include aphotodiode region (not shown) and a well region (not shown) each formedin the substrate 110.

Although not shown, an isolation layer (not shown) defining an activeregion (not shown) and a floating diffusion region FD (see FIG. 7) maybe further formed on the first surface 110F1 of the substrate 110.

A front side structure 130 may be disposed on the first surface 110F1 ofthe substrate 110. The front side structure 130 may include a gateelectrode 132, a wiring layer 134, and an insulation layer 136.

The gate electrode 132 may be disposed on the first surface 110F1 of thesubstrate 110 and may configure a plurality of transistors.

For example, the plurality of transistors may include a transmissiontransistor TX, a reset transistor RX, a drive transistor DX, and aselection transistor SX. The transmission transistor TX may beconfigured to transmit an electrical charge to the floating diffusionregion FD, where the electrical charge is generated in the photoelectricconversion region 120. The reset transistor RX may be configured toperiodically reset an electrical charge stored in the floating diffusionregion FD. The drive transistor DX may be configured to act as a sourcefollower buffer amplifier and to buffer a signal based on the electricalcharge charged into the floating diffusion region FD. The selectiontransistor SX may be configured to perform a switching and addressingoperation of selecting a plurality of image sensing pixels IPX. However,the plurality of transistors are not limited thereto.

In FIG. 4, the gate electrode 132 is illustrated as being formed as aplanar type on the first surface 110F1 of the substrate 110, but somegate electrodes 132 may be formed as a recess gate type which extendsfrom the first surface 110F1 of the substrate 110 to an inner portion ofthe substrate 110.

The wiring layer 134 may be electrically connected to the gate electrode132 or the active region. The wiring layer 134 may include tungsten,aluminum, copper, tungsten, tungsten silicide, titanium silicide,tungsten nitride, titanium nitride, doped polysilicon, and/or the like.The insulation layer 136 may cover the wiring layer 134 on the firstsurface 110F1 of the substrate 110. Additionally, the insulation layer136 may include an insulating material such as silicon oxide, siliconnitride, or silicon oxynitride.

Optionally, a supporting substrate 140 may be disposed on the front sidestructure 130. An adhesive member (not shown) may be further disposedbetween the supporting substrate 140 and the front side structure 130.

The pixel separation structure 150 may be disposed to pass through thesubstrate 110 and may physically and electrically separate one imagesensing pixel IPX from an image sensing pixel IPX adjacent thereto. In aplan view, the pixel separation structure 150 may be disposed in a meshshape or a grid shape. As illustrated in FIG. 4, the pixel separationstructure 150 may extend from the first surface 110F1 to the secondsurface 110F2 of the substrate 110. A width of the pixel separationstructure 150 at the same level as the first surface 110F1 of thesubstrate 110 may be greater than a width of the pixel separationstructure 150 at the same level as the second surface 110F2 of thesubstrate 110. However, the present embodiment is not limited thereto.

The pixel separation structure 150 may include a conductive layer 152and an insulation liner 154, and the insulation liner 154 may bedisposed between the conductive layer 152 and the substrate 110. Inembodiments of the present disclosure, the conductive layer 152 mayinclude a conductive material such as polysilicon or a metal. Theinsulation liner 154 may include a metal oxide such as hafnium oxide,aluminum oxide, or tantalum oxide, and in this case, the insulationliner 154 may act as a negative fixed charge layer. In otherembodiments, the insulation liner 154 may include an insulating materialsuch as silicon oxide, silicon nitride, or silicon oxynitride.

A color filter fence 160 may be disposed on the second surface 110F2 ofthe substrate 110. As exemplarily illustrated in FIG. 5, the colorfilter fence 160 may have a grid shape or a mesh shape in a plan view,and the color filter fence 160 may be disposed to overlap the pixelseparation structure 150 vertically. The color filter fence 160 maydefine a plurality of color filter spaces 160S where a color filterlayer 170 is disposed.

The plurality of color filter spaces 160S may include a first colorfilter space 160S1 disposed at a position overlapping the plurality ofimage sensing pixels IPX and a second color filter space 160S2 disposedat a position overlapping the plurality of phase detection shared pixelsPPX. A color filter layer 170 corresponding to the plurality of imagesensing pixels IPX may be disposed in the first color filter space160S1. Additionally, a color filter layer 170 corresponding to theplurality of phase detection shared pixels PPX may be disposed in thesecond color filter space 160S2. The second color filter space 160S2 maybe disposed to vertically overlap some or all of the first and secondphase detection subpixels PPXa and PPXb. Additionally, the second colorfilter space 160S2 may have a flat area, where the flat area may bewider than that of the first color filter space 16051.

The color filter fence 160 may include a barrier metal pattern 162 and alow refractive index material layer pattern 164 disposed on the barriermetal pattern 162. For example, the low refractive index material layerpattern 164 may have a first refractive index which is greater thanabout 1.0 and is less than or equal to about 1.4. In embodiments of thepresent disclosure, the low refractive index material layer pattern 164may include at least one of polymethylmethacrylate (PMMA), siliconacrylate, cellulose acetatebutyrate (CAB), silica, and fluoro-siliconacrylate (FSA). For example, the low refractive index material layerpattern 164 may include a polymer material where silica (SiOx) particlesare dispersed.

Light traveling toward the color filter fence 160 may be reflected anddirected in a direction toward a center portion of the plurality ofimage sensing pixels IPX, since the low refractive index material layerpattern 164 has the first refractive index which is relatively low. Thecolor filter fence 160 may prevent light, traveling at an inclined angleto an inner portion of a color filter layer 170 disposed on one imagesensing pixel IPX, from entering a color filter layer 170 disposed on anadjacent image sensing pixel IPX. Therefore, preventing interferencefrom occurring between the plurality of image sensing pixels IPX.

The color filter fence 160 may include a first fence part 160I and asecond fence part 160P. The first fence part 160I may vertically overlapa boundary between the plurality of image sensing pixels IPX (forexample, a portion of the pixel separation structure 150 between theplurality of image sensing pixels IPX). The second fence part 160P mayvertically overlap a boundary between one of the plurality of phasedetection shared pixels PPX and an image sensing pixel IPX adjacentthereto in the first direction (the X direction). For example, the firstcolor filter space 160S1 may be limited by the first fence part 160I(or, in a plan view, the first color filter space 16051 may besurrounded by the first fence part 160I), and the second color filterspace 160S2 may be limited by the first fence part 160I and the secondfence part 160P (or, in a plan view, the second color filter space 160S2may be surrounded by the first fence part 160I and the second fence part160P).

The first fence part 160I may have a first width w11 in the firstdirection (the X direction), and the second fence part 160P may have asecond width w12 greater than the first width w11 in the first direction(the X direction). The second width w12 of the second fence part 160Pmay be 1.5 to 10 times the first width w11, but is not limited thereto.A separation ratio characteristic of a phase difference of the pluralityof phase detection shared pixels PPX may be enhanced since the secondfence part 160P is formed to have a relatively large width.

Optionally, a rear insulation layer 166 may be disposed between thesecond surface 110F2 of the substrate 110 and the color filter fence160. Additionally, a passivation layer 168 may be conformally disposedon an upper surface and a side surface of the color filter fence 160.The rear insulation layer 166 may include a metal oxide, such as hafniumoxide, aluminum oxide, or tantalum oxide, or an insulating material suchas silicon oxide, silicon nitride, silicon oxynitride, or a low-kdielectric material. The passivation layer 168 may include an insulatingmaterial such as silicon oxide, silicon nitride, silicon oxynitride, ora low-k dielectric material.

The color filter layer 170 filling the color filter space 160S may bedisposed on the color filter fence 160 and the passivation layer 168.The color filter layer 170 may sense green light, blue light, and redlight based on a kind of material included in the color filter layer170. Herein, for convenience, a color filter layer 170 for sensinggreen, a color filter layer 170 for sensing blue, and a color filterlayer 170 for sensing red may be respectively referred to as a greencolor filter layer G, a blue color filter layer B, and a red colorfilter layer R.

The micro-lens structure 180 may be disposed on the color filter fence160 and the color filter layer 170. A capping layer 190 may be disposedon the micro-lens structure 180.

The micro-lens structure 180 may include a first micro-lens 182 and asecond micro-lens 184. The first micro-lens 182 may be disposed on theplurality of image sensing pixels IPX, and the second micro-lens 184 maybe disposed on the plurality of phase detection shared pixels PPX. Forexample, the second micro-lens 184 may be disposed to vertically overlapsome or all of the first and second phase detection subpixels PPXa andPPXb disposed next to each other in the first direction (the Xdirection). Therefore, the second micro-lens 184 may have a width whichis about twice a width of the first micro-lens 182 in the firstdirection (the X direction).

In embodiments of the present disclosure, a center line of the secondmicro-lens 184 in the first direction (the X direction) may verticallyoverlap the pixel separation structure 150. Particularly, a curvaturecenter of the second micro-lens 184 may vertically overlap a portion ofthe pixel separation structure 150 disposed between the first phasedetection subpixel PPXa and the second phase detection subpixel PPXb.Therefore, light incident on a left side with respect to the center lineof the second micro-lens 184 may be received by the second phasedetection subpixel PPXb, and light incident on a right side may bereceived by the first phase detection subpixel PPXa. Therefore, adetermination of whether an object 2000 (see FIG. 1) is located at anin-focus position may be based on a difference between the amount oflight received by the first phase detection subpixel PPXa and the amountof light received by the second phase detection subpixel PPXb.

In embodiments of the present disclosure, the first micro-lens 182 mayhave a first height h11, and the second micro-lens 184 may have a secondheight h12, which is greater than the first height h11. In someembodiments, the second height h12 may be about 110% to about 300% ofthe first height h11, but is not limited thereto. The second height h12of the second micro-lens 184 may be greater than the first height h11 ofthe first micro-lens 182. Therefore, the phase detection shared pixelPPX may increase AF separation ratio characteristics.

For example, the phase detection shared pixels PPX may be distributedand disposed in the pixel array PXA. Therefore, in a comparativeembodiment, a micro-lens for the image sensing pixel IPX and amicro-lens for the phase detection shared pixel PPX may be formed by thesame photoresist patterning process and etch-back process. However, byusing the same photoresist patterning process and etch-back process, amicro-lens for the image sensing pixel IPX and a micro-lens for thephase detection shared pixel PPX may be formed to have the same height.For example, in a case where a micro-lens is formed to have a height (ora curvature) for light reception by the image sensing pixel IPX, an AFseparation ratio characteristic of the phase detection shared pixel PPXmay be reduced by the micro-lens with such a height. For example, in acase where a micro-lens is formed to have a height (or a curvature) forthe AF separation ratio characteristic of the phase detection sharedpixel PPX, a signal-to-noise ratio (SNR) characteristic of the imagesensing pixel IPX may be reduced by the micro-lens with the height.

According to embodiments, the second micro-lens 184 may be formed tohave the second height h12 which is greater than a height of the firstmicro-lens 182. Therefore, the first micro-lens 182 may have a curvature(or a height) optimized for the SNR characteristic of the image sensingpixel IPX and the second micro-lens 184 may have a curvature (or aheight) optimized for the AF separation ratio characteristic of thephase detection shared pixel PPX.

Also, as described above, the second fence part 160P of the color filterfence 160 disposed under the second micro-lens 184 may have the secondwidth w12, which is greater than a width of the first fence part 160I ofthe color filter fence 160 disposed under the first micro-lens 182. Adifference between the amount of light incident on the first phasedetection subpixel PPXa through the second micro-lens 184 and the amountof light incident on the second phase detection subpixel PPXb throughthe second micro-lens 184 may increase, for example, the AF separationratio characteristic may be enhanced, since the second fence part 160Pis formed to a relatively large width.

As exemplarily illustrated in FIGS. 3 and 5, the plurality of imagesensing pixels IPX may include a plurality of image sensing sharedpixels SIPX. For example, the plurality of image sensing shared pixelsSIPX may include two pixels adjacent to each other in the firstdirection and two pixels adjacent to each other in the second direction.For example, in FIG. 3, one image sensing shared pixel SIPX may includefirst to fourth image sensing subpixels IPX1 to IPX4 arranged in a 2×2matrix form. However, the inventive concept is not limited thereto, andone image sensing shared pixel SIPX may include nine subpixels arrangedin a 3×3 matrix form or may include sixteen subpixels arranged in a 4×4matrix form.

The color filter layer 170 for sensing the same color may be disposed onthe first to fourth image sensing subpixels IPX1 to IPX4 included in oneimage sensing shared pixel SIPX. For example, a green color filter layerG may be disposed on the first to fourth image sensing subpixels IPX1 toIPX4 illustrated by a dashed line in FIG. 3. For example, a blue colorfilter layer B and the green color filter layer G may be alternatelydisposed on a plurality of image sensing shared pixels SIPX arranged inthe first direction (the X direction). The blue color filter layer B andthe green color filter layer G may be alternately disposed on aplurality of image sensing shared pixels SIPX arranged in the seconddirection (the Y direction). However, the color arrangement of the colorfilter layer 170 is not limited to the above description. In otherembodiments, at least a portion of the green color filter layer G may bereplaced by a color filter layer 170, which senses white.

In one shared pixel SIPX_B illustrated in FIG. 5, the blue color filterlayer B may be disposed in the first color filter space 160S1 limited bythe first fence part 160I of the color filter fence 160. For example, inthe one shared pixel SIPX_B, the blue color filter layer B may bedisposed on each of first to fourth image sensing subpixels IPX1 toIPX4, and in one shared pixel SIPX_G adjacent thereto, the green colorfilter layer G may be disposed on each of first to fourth image sensingsubpixels IPX1 to IPX4.

In one phase detection shared pixel PPX illustrated in FIG. 4, the greencolor filter layer G may be disposed in the second color filter space160S2 limited by the first fence part 160I and the second fence part160P of the color filter fence 160. In other embodiments, the colorfilter layer 170 for sensing white may be disposed on a plurality ofphase detection shared pixels PPX. In other embodiments, the green colorfilter layer G may be disposed on some of a plurality of phase detectionshared pixels PPX, and the color filter layer 170 for sensing white maybe disposed on some other phase detection shared pixels PPX.

The phase detection shared pixel PPX may be disposed at a position of asubpixel of two adjacent image sensing shared pixels SIPX. Therefore,each of peripheral shared pixels SIPX_P1 and SIPX_P2 disposed adjacentto the phase detection shared pixel PPX may include first to third imagesensing subpixels IPX1 to IPX3. For example, the peripheral shared pixelSIPX_P1 disposed at a left side of the phase detection shared pixel PPXillustrated in FIG. 5 may be configured with three subpixelscorresponding to the blue color filter layer B. Additionally, theperipheral shared pixel SIPX_P2 disposed at a right side of the phasedetection shared pixel PPX may be configured with three subpixelscorresponding to a red color filter layer R. However, the arrangement ofthe phase detection shared pixel PPX is not limited thereto.

In embodiments of the present disclosure, in a low illuminationoperation mode, control may be performed to generate a pixel signal bysensing light through a plurality of photoelectric conversion regions120 of a plurality of image sensing shared pixels SIPX. Also, in a highillumination operation mode, control may be performed to individuallygenerate a pixel signal based on each of image sensing subpixels IPX1 toIPX4 of the plurality of image sensing shared pixels SIPX. For example,under a low illumination condition, a pixel signal may be generatedbased on one unit including some or all of four image sensing subpixelsIPX1 to IPX4. Under a high-resolution condition, a pixel signal may begenerated based on one unit including each of four image sensingsubpixels IPX1 to IPX4. Therefore, even when a light-receiving capacity(or a light receiving area) of one subpixel is reduced because a size ofa unit pixel is reduced based on the scale-down of the image sensor 100,a wide dynamic range may be secured.

Also, according to the image sensor 100 described above, the secondmicro-lens 184 may be formed to have the second height h12, which isgreater than the first height h11 of the first micro-lens 182.Therefore, the first micro-lens 182 may have a curvature (or a height)optimized for the SNR characteristic of the image sensing pixel IPX andthe second micro-lens 184 may have a curvature (or a height) optimizedfor the AF separation ratio characteristic of the phase detection sharedpixel PPX. Also, the second width w12 of the second fence 160P of thecolor filter fence 160 may be set to be greater than the first width w11of the first fence part 160I. Therefore, the AF separation ratiocharacteristic of the phase detection shared pixel PPX may be enhanced.Therefore, the image sensor 100 may quickly and accurately perform theAF function and may enhance a sensitivity of an image sensing pixel.

FIG. 7 is an equivalent circuit diagram of a plurality of pixels PX ofan image sensor 100 according to embodiments.

Referring to FIG. 7, the plurality of pixels PX may be arranged in amatrix form. Each of the plurality of pixels PX may include atransmission transistor TX and a plurality of logic transistors. Here,the logic transistors may include a reset transistor RX, a selectiontransistor SX, and a drive transistor DX (or a source followertransistor). The reset transistor RX may include a reset gate RG, theselection transistor SX may include a selection gate SG, and thetransmission transistor TX may include a transmission gate TG.

Each of the plurality of pixels PX may further include a photoelectricconversion device PD and a floating diffusion region FD. Thephotoelectric conversion device PD may correspond to the photoelectricconversion region 120 described above with reference to FIGS. 3 to 6.The photoelectric conversion device PD may generate and accumulatephotoelectric charges in proportion to the amount of light incident fromthe outside and may use a photodiode, a phototransistor, a photogate, apinned photodiode (PPD), and a combination thereof.

The transmission gate TG may transmit a photoelectric charge, generatedby the photoelectric conversion device PD, to the floating diffusionregion FD. The floating diffusion region FD may receive, accumulate, andstore the photoelectric charge generated by the photoelectric conversiondevice PD. The drive transistor DX may be controlled based on the amountof photoelectric charges accumulated into the floating diffusion regionFD.

The reset transistor RX may periodically reset photoelectric chargesaccumulated into the floating diffusion region FD. A drain electrode ofthe reset transistor RX may be connected to the floating diffusionregion 1-D, and a source electrode thereof may be connected to a sourcevoltage V_(DD). When the reset transistor RX is turned on, the sourcevoltage V_(DD) connected to the source electrode of the reset transistorRX may be transferred to the floating diffusion region FD. When thereset transistor RX is turned on, the photoelectric charges accumulatedinto the floating diffusion region FD may be discharged. Therefore, thefloating diffusion region FD may be reset.

The drive transistor DX may be connected to a current source (not shown)disposed outside the plurality of pixels PX and may act as a sourcefollower buffer amplifier, and moreover, the drive transistor DX mayamplify an electric potential variation in the floating diffusion regionFD and may output the amplified electric potential variation to anoutput line V_(OUT).

The selection transistor SX may select the plurality of pixels PX byunits of rows, and when the selection transistor SX is turned on, thesource voltage V_(DD) may be transferred to a source electrode of thedrive transistor DX.

FIG. 8 is a cross-sectional view illustrating an image sensor 100Aaccording to embodiments, and FIG. 9 is a horizontal cross-sectionalview of a region corresponding to CX1 of FIG. 3. In FIGS. 8 and 9, thesame reference numerals as those of FIGS. 1 to 7 refer to like elements.

Referring to FIGS. 8 and 9, a micro-lens structure 180A may include afirst micro-lens 182 and a second micro-lens 184A, and the secondmicro-lens 184A may include a bottom micro-lens part 184AB and a topmicro-lens part 184AT. The bottom micro-lens part 184AB may be disposedon a color filter fence 160 and a color filter layer 170, and the topmicro-lens part 184AT may be disposed on the bottom micro-lens part184AB.

In embodiments of the present disclosure, the bottom micro-lens part184AB and the top micro-lens part 184AT may be provided as one body andmay be configured as one material layer. The bottom micro-lens part184AB and the top micro-lens part 184AT may be portions of asemispherical structure with different curvature radii (or curvaturecenters). A boundary line 184AC between the bottom micro-lens part 184ABand the top micro-lens part 184AT may correspond to a connection linebetween points at which a curvature of the second micro-lens 184A variesrapidly. Additionally, a portion of the second micro-lens 184A on theboundary line 184AC may be referred to as the top micro-lens part 184AT.A portion of the second micro-lens 184A under the boundary line 184ACmay also be referred to as the bottom micro-lens part 184AB. Asillustrated in FIG. 9, the top micro-lens part 184AT may have asemispherical shape that extends in a first direction (an X direction).In a plan view, the boundary line 184AC may have an oval shape thatextends in the first direction (the X direction).

In embodiments of the present disclosure, the second micro-lens 184A mayhave a second height h12 a, which is greater than a first height h11 ofthe first micro-lens 182. Therefore, the first micro-lens 182 may have acurvature (or a height) optimized for an SNR characteristic of an imagesensing pixel IPX and the second micro-lens 184A may have a curvature(or a height) optimized for an AF separation ratio characteristic of aphase detection shared pixel PPX. Also, the second micro-lens 184A maybe provided to include the bottom micro-lens part 184AB and the topmicro-lens part 184AT with different curvatures. Therefore, the secondmicro-lens 184A may have a characteristic optimized for the AFseparation ratio characteristic of the phase detection shared pixel PPX.

FIG. 10 is a cross-sectional view illustrating an image sensor 100Baccording to embodiments. FIG. 10 is a plan view of a regioncorresponding to CX1 of FIG. 3. In FIG. 10, the same reference numeralsas those of FIGS. 1 to 9 refer to like elements.

A micro-lens structure 180B may include a first micro-lens 182 and asecond micro-lens 184B, and the second micro-lens 184B may include abottom micro-lens part 184BB and a top micro-lens part 184BT. The bottommicro-lens part 184BB and the top micro-lens part 184BT may be portionsof a semispherical structure with different curvature radii (orcurvature centers). As illustrated in FIG. 10, the top micro-lens part184 bT may have a semispherical shape where a width thereof in a seconddirection (a Y direction) is similar to a width thereof in a firstdirection (an X direction). In a plan view, a boundary line 184BC mayinclude a portion overlapping a first phase detection subpixel PPXa anda portion overlapping a second phase detection subpixel PPXb. The secondmicro-lens 184B may have a shape or a curvature (or a height) optimizedfor an AF separation ratio characteristic of a phase detection sharedpixel PPX.

FIG. 11 is a cross-sectional view illustrating an image sensor 100Caccording to embodiments. FIG. 11 is a cross-sectional view of a regioncorresponding to a line A1-A1′ of FIG. 3. In FIG. 11, the same referencenumerals as those of FIGS. 1 to 10 refer to like elements.

Referring to FIG. 11, a micro-lens structure 180C may include a firstmicro-lens 182 and a second micro-lens 184C, and the second micro-lens184C may include a bottom micro-lens part 184CB and a top micro-lenspart 184CT. The bottom micro-lens part 184CB and the top micro-lens part184CT may include different materials.

For example, the bottom micro-lens part 184CB may include alight-transmitting organic material, and the top micro-lens part 184CTmay include a photoresist material. The bottom micro-lens part 18CB maybe formed by etching back a light-transmitting organic material, and thetop micro-lens part 184CT may be formed by reflowing a photoresistmaterial.

In embodiments of the present disclosure, the first micro-lens 182 mayhave a first height h11, the bottom micro-lens part 184CB may have asecond height h22 a, and the top micro-lens part 184CT may have a thirdheight h22 b. The second height h22 a may be substantially the same asor similar to the first height h11, but is not limited thereto.

FIG. 12 is a layout view illustrating an image sensor 100D according toembodiments, and FIG. 13 is a plan view of a region CX2 of FIG. 12. InFIGS. 12 and 13, the same reference numerals as those of FIGS. 1 to 11refer to like elements.

Referring to FIGS. 12 and 13, a phase detection shared pixel PPX may bedisposed at a position of a subpixel of one image sensing shared pixelSIPX. Therefore, a peripheral shared pixel SIPX_P disposed adjacent tothe phase detection shared pixel PPX may include first and second imagesensing subpixels IPX1 and IPX2. For example, a shared pixel SIPX_Pdisposed under the phase detection shared pixel PPX, illustrated in FIG.13, may be configured with two subpixels (or where a green color filterlayer G is provided thereon) corresponding to the green color filterlayer G. One shared pixel SIPX_R disposed at a right side of the phasedetection shared pixel PPX may be configured with four subpixelscorresponding to a red color filter layer R. However, the arrangement ofthe phase detection shared pixel PPX is not limited thereto.

FIG. 14 is a layout view illustrating an image sensor 100E according toembodiments.

Referring to FIG. 14, a first phase detection shared pixel PPXE1 mayinclude first and second phase detection subpixels PPXa1 and PPXb1disposed next to each other in a first direction (an X direction).Additionally, the first phase detection shared pixel PPXE1 may include asecond phase detection shared pixel PPXE2 may include third and fourthphase detection subpixels PPXa2 and PPXb2 disposed next to each other ina second direction (a Y direction).

In some embodiments, the first phase detection shared pixel PPXE1 may becontrolled to calculate an in-focus position in a horizontal direction(e.g., the X-direction), and the second phase detection shared pixelPPXE2 may be controlled to calculate an in-focus position in a verticaldirection (e.g., the Y direction). A plurality of first phase detectionshared pixels PPXE1 and a plurality of second phase detection sharedpixels PPXE2 may be randomly distributed and arranged. The number offirst phase detection shared pixels PPXE may be the same as the numberof second phase detection shared pixels PPXE2. In other embodiments, thenumber and arrangement of first phase detection shared pixels PPXE andthe number and arrangement of second phase detection shared pixels PPXE2may be modified.

FIGS. 15 to 25 are cross-sectional views illustrating a method ofmanufacturing an image sensor 100 according to embodiments. FIGS. 15 to25 illustrate, in a process sequence, cross-sectional surfacescorresponding to a cross-sectional surface taken along line A1-A1′ ofFIG. 3. In FIGS. 15 to 25, the same reference numerals as those of FIGS.1 to 14 refer to like elements.

Referring to FIG. 15, a substrate 110 including a first surface 110F1and a second surface 110F2 opposite to each other may be provided. Amask pattern (not shown) may be formed on the first surface 110F1 of thesubstrate 110. A trench 150T may be formed by removing a portion of thesubstrate 110 from the first surface 110F1 of the substrate 110 by usingthe mask pattern.

Subsequently, an insulation liner 154 and a conductive layer 152 may besequentially formed in the trench 150T. A pixel separation structure 150may be formed in the trench 150T by removing the insulation liner 154and the conductive layer 152 portion disposed on the first surface 110F1of the substrate 110 through a planarization process.

Subsequently, a photoelectric conversion region 120 including aphotodiode region (not shown) and a well region (not shown) may beformed from the first surface 110F1 of the substrate 110 by an ionimplantation process. For example, the photodiode region may be formedby doping N-type impurities, and the well region may be formed by dopingP-type impurities.

Referring to FIG. 16, a front side structure 130 may be formed on thefirst surface 110F1 of the substrate 110. First, a gate electrode 132may be formed on the first surface 110F1 of the substrate 110. Then, afloating diffusion region (not shown) and an active region (not shown)may be formed in a partial region of the first surface 110F1 of thesubstrate 110 by performing an ion implantation process. Next, a wiringlayer 134 and an insulation layer 136 may be formed on the substrate 110by repeatedly performing an operation of forming a conductive layer (notshown) on the first surface 110F1 of the substrate 110, an operation ofpatterning the conductive layer, and an operation of forming aninsulation layer (not shown) to cover the patterned conductive layer.

Subsequently, a supporting substrate 140 may be attached on theinsulation layer 136.

Referring to FIG. 17, the substrate 110 may be overturned so that thesecond surface 110F2 of the substrate 110 faces upward. Here, a bottomsurface of the trench 150T may be in a state which is not exposed at thesecond surface 110F2 of the substrate 110.

Referring to FIG. 18, a portion of the substrate 110 may be removed fromthe second surface 110F2 of the substrate 110 through a planarizationprocess such as a chemical mechanical planarization (CMP) process or anetch-back process so that the conductive layer 152 is exposed. As such aremoval process is performed, a level of the second surface 110F2 of thesubstrate 110 may be lowered. At this time, one image sensing pixel IPXsurrounded by the pixel separation structure 150 may be physically andelectrically separated from an image sensing pixel IPX adjacent thereto.

Referring to FIG. 19, a rear insulation layer 166 may be formed on thesecond surface 110F2 of the substrate 110.

Subsequently, a barrier metal layer (not shown) and a low refractiveindex material layer (not shown) may be sequentially formed on the rearinsulation layer 166, and a barrier metal pattern 162 and a lowrefractive index material layer pattern 164 may be formed by patterningthe barrier metal layer and the low refractive index material layer. Thebarrier metal pattern 162 and the low refractive index material layerpattern 164 may be referred to as a color filter fence 160, and in aplan view, may each have a grid shape and may vertically overlap thepixel separation structure 150.

In the patterning process, the color filter fence 160 may be patternedto include a first fence part 160I with a relatively small width and asecond fence part 160P with a relatively large width. Here, a colorfilter space 160S may be defined by the color filter fence 160, a firstcolor filter space 160S1 may overlap an image sensing pixel IPX, and asecond color filter space 160S2 may overlap a phase detection sharedpixel PPX.

Subsequently, a passivation layer 168 may be conformally formed on aninner wall of the color filter space 160S.

Referring to FIG. 20, a color filter layer 170 may be formed in thecolor filter space 160S.

Referring to FIG. 21, a micro-lens material layer 180L may be formed onthe color filter layer 170. For example, the micro-lens material layer180L may be formed of a light-transmitting organic material through aspin coating process, a chemical vapor deposition (CVD) process, or thelike.

Referring to FIG. 22, a plurality of first mask patterns 322P1 may beformed on the micro-lens material layer 180L at positions overlapping aplurality of image sensing pixels IPX. Each of the first mask patterns322P1 may include a photoresist pattern. For example, to form the firstmask patterns 322P1, a photoresist material may be spin-coated. Then, anexposure process, a baking process, and a development process may besequentially performed.

Referring to FIG. 23, a plurality of second mask patterns 324P1 may beformed on the micro-lens material layer 180L at a position overlappingthe phase detection shared pixel PPX. Each of the second mask patterns324P1 may include a photoresist pattern. Each of the second maskpatterns 324P1 may be formed to have a height and a width which aregreater than those of each of the first mask patterns 322P1. Also, eachof the second mask patterns 324P1 may be disposed at a positionvertically overlapping all of first and second phase detection subpixelsPPXa and PPXb.

Referring to FIG. 24, the plurality of first mask patterns 322P1 may bechanged to a plurality of first reflow patterns 322R1 and the pluralityof second mask patterns 324P1 may be changed to a plurality of secondreflow patterns 324R1 by performing a reflow process.

In embodiments of the present disclosure, due to heat which is suppliedin the reflow process, the plurality of first mask patterns 322P1 andthe plurality of second mask patterns 324P1 may each be changed to asemispherical shape. Therefore, the plurality of first reflow patterns322R1 and the plurality of second reflow patterns 324R1 may be formed.

In embodiments of the present disclosure, the reflow process may beperformed for several seconds to tens of minutes at a temperature ofabout 100° C. to about 200° C., but is not limited thereto.

Referring to FIG. 25, by etching the micro-lens material layer 180Lusing the plurality of first reflow patterns 322R1 and the plurality ofsecond reflow patterns 324R1 as an etch mask, a shape of each of theplurality of first reflow patterns 322R1 and a shape of each of theplurality of second reflow patterns 324R1 may be transferred to thefirst micro-lens 182 and the second micro-lens 184. At this time, anedge portion of the first micro-lens 182 may be connected to an edgeportion of the second micro-lens 184.

Subsequently, a capping layer 190 may be formed on a micro-lensstructure 180, including the first micro-lens 182 and the secondmicro-lens 184.

According to the above-described embodiments, the plurality of firstmask patterns 322P1 may be first formed. Then the plurality of secondmask patterns 324P1 may be formed to have a relatively larger height.Subsequently, the plurality of first mask patterns 322P1 and theplurality of second mask patterns 324P1 may be reflowed, and byperforming an etch process, the micro-lens structure 180 may be formed.The image sensor 100 manufactured by the above-described method mayquickly and accurately perform the AF function, thereby enhancing asensitivity of an image sensing pixel.

Thus, according to an embodiment of the inventive concept, a method ofmanufacturing an image sensor is described. The method may includeproviding a plurality of pixels on a substrate, wherein the plurality ofpixels includes one or more first pixels and one or more second pixels;providing a first micro-lens on each of the one or more first pixelsusing a first process; and providing a second micro-lens on each of theone or more second pixels using a second process, wherein the firstmicro-lens comprises a different shape from the second micro-lens.

In some cases, the method further comprises forming a micro-lensmaterial layer over the plurality of image sensing pixels, wherein thefirst process comprises: forming a first mask pattern; forming a firstreflow pattern based on the first mask pattern; and forming the firstmicro-lens from the micro-lens material layer based on the first reflowpattern; and wherein the second process comprises: forming a second maskpattern; forming a second reflow pattern based on the second maskpattern; and forming the second micro-lens based on the second reflowpattern.

In some cases, the one or more first pixels comprise image sensingpixels; and the one or more second pixels comprise phase detectionshared pixels configured to generate a phase signal for calculating aphase difference between images. In some cases, a height of the secondmicro-lens is greater than a height of the first micro-lens.

FIGS. 26 to 28 are cross-sectional views illustrating a method ofmanufacturing an image sensor 100 according to embodiments.

First, the processes described above with reference to FIGS. 15 to 21may be performed.

Referring to FIG. 26, a plurality of second mask patterns 324P2 may befirst formed on a micro-lens material layer 180L at a positionoverlapping a phase detection shared pixel PPX.

Referring to FIG. 27, each of a plurality of first mask patterns 322P2may be formed on the micro-lens material layer 180L at positionsoverlapping a plurality of image sensing pixels IPX. Each of the firstmask patterns 322P2 may be formed to have a height and a width which areless than those of each of the second mask patterns 322P2.

Referring to FIG. 28, the plurality of first mask patterns 322P2 may bechanged to a plurality of first reflow patterns 322R2 and the pluralityof second mask patterns 324P2 may be changed to a plurality of secondreflow patterns 324R2 by performing a reflow process.

Subsequently, the image sensor 100 may be finished by performing theprocess described above with reference to FIG. 25.

FIGS. 29 to 32 are cross-sectional views illustrating a method ofmanufacturing an image sensor 100 according to embodiments.

First, the processes described above with reference to FIGS. 15 to 21may be performed.

Referring to FIG. 29, a plurality of first mask patterns 324P3 may beformed on a micro-lens material layer 180L at positions overlapping aplurality of image sensing pixels IPX.

Referring to FIG. 30, by performing a first reflow process, theplurality of first mask patterns 322P3 may be respectively changed to aplurality of first reflow patterns 322R3.

Referring to FIG. 31, a plurality of second mask patterns 324P3 may beformed on the micro-lens material layer 180L at a position overlapping aphase detection shared pixel PPX.

Referring to FIG. 32, the plurality of second mask patterns 324P3 may berespectively changed to a plurality of second reflow patterns 324R3 byperforming a second reflow process. A shape of each of the plurality offirst reflow patterns 322R3 may not be significantly changed in thesecond reflow process, since a shape of each of the plurality of firstreflow patterns 322R3 has been changed to a semispherical shape in thefirst reflow process.

Subsequently, the image sensor 100 may be finished by performing theprocess described above with reference to FIG. 25.

FIGS. 33 to 36 are cross-sectional views illustrating a method ofmanufacturing an image sensor 100A according to embodiments.

First, the processes described above with reference to FIGS. 15 to 21may be performed.

Referring to FIG. 33, a plurality of first mask patterns 332P1 may beformed on a micro-lens material layer 180L at positions overlapping aplurality of image sensing pixels IPX, and a plurality of second maskpatterns 334P1 may be formed on the micro-lens material layer 180L at aposition overlapping a phase detection shared pixel PPX. The pluralityof first mask patterns 332P1 and the plurality of second mask patterns334P1 may be formed in the same photoresist patterning process.Therefore, the plurality of first mask patterns 332P1 and the pluralityof second mask patterns 334P1 may be formed to have the same height.

Referring to FIG. 34, a plurality of third mask patterns 334P2 may beformed on the plurality of second mask patterns 334P1 at a positionoverlapping a phase detection shared pixel PPX. A width and a height ofeach of the plurality of third mask patterns 334P2 may be determinedbased on a curvature and a shape of a second micro-lens 184A which is tobe formed in a subsequent process. For example, in a case where theplurality of third mask patterns 334P2 are formed to have a width whichis less than that of the plurality of second mask patterns 334P1 asillustrated in FIG. 34, the second micro-lens 184A may be formed to havedifferent curvatures (or curvature radii) of an upper portion and alower portion thereof. Alternatively, in a case where the plurality ofthird mask patterns 334P2 are formed to have substantially the samewidth as that of the plurality of second mask patterns 334P1, asillustrated in FIG. 4, the second micro-lens 184 may be formed to have asemispherical shape where a whole surface thereof has substantially thesame curvature center.

Referring to FIG. 35, the plurality of first mask patterns 332P1 may bechanged to a plurality of first reflow patterns 332R1 and the pluralityof second mask patterns 334P1 may be changed to a plurality of secondreflow patterns 334R1 by performing a reflow process.

Referring to FIG. 36, by etching the micro-lens material layer 180Lusing the plurality of first reflow patterns 332R1 and the plurality ofsecond reflow patterns 334R1 as an etch mask, a shape of each of theplurality of first reflow patterns 332R1 and a shape of each of theplurality of second reflow patterns 334R1 may be transferred to thefirst micro-lens 182 and the second micro-lens 184A.

FIGS. 37 to 40 are cross-sectional views illustrating a method ofmanufacturing an image sensor, according to embodiments.

First, the processes described above with reference to FIGS. 15 to 21may be performed.

Referring to FIG. 37, a plurality of first mask patterns 342P1 may beformed on a micro-lens material layer 180L at positions overlapping aplurality of image sensing pixels IPX, and a plurality of second maskpatterns 344P1 may be formed on the micro-lens material layer 180L at aposition overlapping a phase detection shared pixel PPX. The pluralityof first mask patterns 342P1 and the plurality of second mask patterns344P1 may be formed in the same photoresist patterning process.Therefore, the plurality of first mask patterns 342P1 and the pluralityof second mask patterns 344P1 may be formed to have the same height.

Referring to FIG. 38, the plurality of first mask patterns 342P1 may bechanged to a plurality of first reflow patterns 342R1 and the pluralityof second mask patterns 344P1 may be changed to a plurality of secondreflow patterns 344R1 by performing a reflow process.

Referring to FIG. 39, a shape of each of the plurality of first reflowpatterns 342R1 and a shape of each of the plurality of second reflowpatterns 344R1 may be transferred to the first micro-lens 182 and abottom micro-lens part 184CB by etching the micro-lens material layer180L. Etching the micro-lens material is performed using the pluralityof first reflow patterns 342R1 and the plurality of second reflowpatterns 344R1 as an etch mask.

The bottom micro-lens part 184CB may be formed to have a second heighth22 a which is substantially the same as or similar to a first heighth11 of the first micro-lens 182.

Subsequently, a plurality of third mask patterns 344P2 may be formed onthe bottom micro-lens part 184CB.

Referring to FIG. 40, the plurality of third mask patterns 344P2 may berespectively changed to a plurality of top micro-lens parts 184CT byperforming a reflow process. The bottom micro-lens part 184CB may beformed in a semispherical shape with a third height h22 b through thereflow process.

Subsequently, a capping layer 190 may be formed on a micro-lensstructure 180 including the first micro-lens 182 and a second micro-lens184C.

According to the above-described embodiments, the first micro-lens 182and a plurality of second micro-lenses 184, 184A, 184B, and 184C may beformed to have different heights. Therefore, the first micro-lens 182may have a curvature (or a height) optimized for an SNR characteristicof an image sensing pixel IPX and the second micro-lenses 184, 184A,184B, and 184C may have a curvature (or a height) optimized for an AFseparation ratio characteristic of a phase detection shared pixel PPX.The image sensors 100 to 100E, manufactured by the above-describedmethod, may quickly and accurately perform the AF function, therebyincreasing a sensitivity of an image sensing pixel.

While the inventive concept has been particularly shown and describedwith reference to embodiments thereof, it will be understood thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the following claims.

What is claimed is:
 1. An image sensor comprising: a pixel array, thepixel array including: a first image sensing subpixel and a second imagesensing subpixel provided in a substrate, each of the first and secondimage sensing subpixels including a photodiode therein; a first phasedetection subpixel and a second phase detection subpixel provided in thesubstrate, each of the first and second phase detection subpixelsincluding a photodiode therein; a first micro-lens disposed on the firstimage sensing subpixel in a first row; a second micro-lens disposed onthe second image sensing subpixel in the first row; and a thirdmicro-lens disposed on the first phase detection subpixel and the secondphase detection subpixel in the first row, the third micro-lens beinglocated adjacent to the first and second micro-lenses, wherein the firstphase detection subpixel is located adjacent to the second phasedetection subpixel, and wherein a first color filter layer disposed onthe first image sensing subpixel and a second color filter layerdisposed on the second image sensing subpixel have a same color.
 2. Theimage sensor of claim 1, wherein the third micro-lens is disposedbetween the first micro-lens and the second micro-lens in the first row.3. The image sensor of claim 1, wherein the first phase detectionsubpixel and the second phase detection subpixel are disposed betweenthe first image sensing subpixel and the second image sensing subpixel.4. The image sensor of claim 1, wherein a third color filter layerdisposed on the first and second phase detection subpixels has a greencolor.
 5. The image sensor of claim 1, wherein the first micro-lens hasa first height, and the third micro-lens has a second height which isgreater than the first height.
 6. The image sensor of claim 1, whereinthe first image sensing subpixel constitutes a first image sensingshared pixel, the first image sensing shared pixel includes four firstimage sensing subpixels arranged in a 2×2 matrix form, and four firstcolor filter layers having a same color are disposed on the four firstimage sensing subpixels.
 7. The image sensor of claim 1, furthercomprising a color filter fence disposed on an upper surface of thesubstrate, the color filter fence defining a plurality of color filterspaces in which a color filter layer is disposed.
 8. The image sensor ofclaim 1, wherein the color filter fence is disposed between the firstimage sensing subpixel and the first phase detection subpixel andbetween the second image sensing subpixel and the second phase detectionsubpixel, and the color filter fence is not disposed between the firstphase detection subpixel and the second phase detection subpixel.
 9. Theimage sensor of claim 7, wherein the color filter fence includes: abarrier metal pattern; and a low refractive index material layer patterndisposed on the barrier metal pattern to have a first refractive index.10. The image sensor of claim 9, wherein the first refractive index isgreater than 1.0 and is less than or equal to 1.4.
 11. An image sensorcomprising: a pixel array, the pixel array including: a first imagesensing subpixel and a second image sensing subpixel provided in asubstrate, each of the first and second image sensing subpixelsincluding a photodiode therein; a first phase detection subpixel and asecond phase detection subpixel provided in the substrate, each of thefirst and second phase detection subpixels including a photodiodetherein, the first and second phase detection subpixels being next toeach other; a first micro-lens disposed on the first image sensingsubpixel in a first row; a second micro-lens disposed on the secondimage sensing subpixel in the first row; a third micro-lens disposed onthe first phase detection subpixel and the second phase detectionsubpixel in the first row and disposed on a third phase detectionsubpixel and a fourth phase detection subpixel in a second row, thethird micro-lens being located adjacent to the first and secondmicro-lenses, a first color filter layer disposed on the first imagesensing subpixel and having a first color; and a second color filterlayer disposed on the second image sensing subpixel and having the firstcolor.
 12. The image sensor of claim 11, wherein the third micro-lens isdisposed between the first micro-lens and the second micro-lens in thefirst row.
 13. The image sensor of claim 11, wherein the first phasedetection subpixel and the second phase detection subpixel are disposedbetween the first image sensing subpixel and the second image sensingsubpixel.
 14. The image sensor of claim 11, further comprising a thirdcolor filter layer disposed on the first and second phase detectionsubpixels and having a second color different from the first color,wherein the second color is green.
 15. The image sensor of claim 11,wherein the first micro-lens has a first height, and the thirdmicro-lens has a second height which is greater than the first height.16. The image sensor of claim 11, wherein the first image sensingsubpixel constitutes a first image sensing shared pixel, the first imagesensing shared pixel includes four first image sensing subpixelsarranged in a 2×2 matrix form, and four first color filter layers havinga same color are disposed on the four first image sensing subpixels. 17.The image sensor of claim 11, further comprising a color filter fencedisposed on an upper surface of the substrate, the color filter fencedefining a plurality of color filter spaces in which a color filterlayer is disposed.
 18. The image sensor of claim 11, wherein the colorfilter fence is disposed between the first image sensing subpixel andthe first phase detection subpixel and between the second image sensingsubpixel and the second phase detection subpixel, and the color filterfence is not disposed between the first phase detection subpixel and thesecond phase detection subpixel.
 19. The image sensor of claim 17,wherein the color filter fence includes: a barrier metal pattern; and alow refractive index material layer pattern disposed on the barriermetal pattern to have a first refractive index.
 20. The image sensor ofclaim 19, wherein the first refractive index is greater than 1.0 and isless than or equal to 1.4.